Magnetically impelled arc butt welding of pipelines

ABSTRACT

The present invention is a method and a vehicle-mounted apparatus ( 30 ) for laying pipelines in which adjacent pipe ( 17, 28 ) are joined by the technique of magnetically impelled arc butt welding (MIAB). A MIAB welding head ( 13 ) having a welding axis is mounted on a transportable platform ( 35 ). A pipe guide ( 50 ) capable of engaging a welded pipe string is located rearwardly of the welding head ( 45 ). The pipe guide ( 50 ) maintains alignment of the string with the welding axis. The apparatus includes pipe feed means ( 47, 48, 49 ) maintaining alignment of a next pipe to be laid with the welding axis and the pipe string ( 17 ). The platform ( 37 ) is rotatably mounted on the vehicle ( 30 ) and tilts around a horizontal axis. The vehicle ( 300 ) is provided with pivoting steerable tracks ( 38 ).

TECHNICAL FIELD

[0001] This invention relates to the laying of pipelines such as gas oroil pipelines, in which successive pipe sections are welded to form astring which is laid in a trench or other line of rest. The inventionprovides a method and apparatus for laying pipelines in which pipesections are joined by the technique of magnetically impelled arc butt(MIAB) welding

BACKGROUND ART

[0002] MIAB welding is a forge-welding process in which a welding arc isestablished in a gap between the parts to be welded, and the arc ismoved by means of a magnetic field. In the MIAB welding of steel pipes,the square edged or otherwise prepared pipe ends to be welded arealigned axially and separated by a small gap, and a welding arcestablished in the gap. A magnetic field is then superimposed on thegap, causing the arc to rotate at high speed around the gap. After theends are heated, they are pressed together causing plastic and moltenmetal present on the heated surfaces to be forced out of the joint,along with oxides and other impurities. A high quality weld is thusproduced.

[0003] Although MIAB welding has been proposed for pipelines, prior artmethods for its implementation have been found wanting.

SUMMARY OF THE INVENTION

[0004] In one aspect the invention includes an apparatus formagnetically impelled arc butt (MIAB) welding including a transportableplatform, a MIAB welding head mounted on said transportable platform,said welding head having a welding axis, a pipe guide located rearwardlyof said welding head and capable of engaging a welded pipe string tomaintain alignment of said string with said welding axis, and pipe feedmea maintaining alignment of a next pipe to be laid with the weldingaxis and the pipe string.

[0005] Preferably said apparatus further includes an outrigger meansextending rearwardly of said platform, said pipe guide being mounted onsaid outrigger means.

[0006] Preferably the platform also includes means for the transfer of apipe from a pipe supply to the pipe feed means, such feed meansincluding an in-feed bed holding the next pipe to be welded in alignmentwith the welding axis and the welded string.

[0007] Preferably the pipe supply includes a pipe magazine mounted onsaid transportable platform.

[0008] The invention also resides in a pipe-laying vehicle includingsaid transportable platform and a travelling body, said transportableplatform being rotatably mounted on said travelling body, and having asubstantially vertical axis of rotation.

[0009] Preferably said pipe-laying vehicle further includes pivotablemounting means for tilting said transportable platform relative to saidtravelling body.

[0010] Preferably said travelling body includes a tracked support havinga direction of travel and said axis of tilt is perpendicular to saiddirection.

[0011] Preferably said travelling body includes at least a pair oftracks for respective sides of said body.

[0012] Preferably said travelling body further includes at least a setof auxiliary wheels spaced from said tracks for supporting saidpipe-laying vehicle, each of said auxiliary wheels being rotatablymounted to a pivot arm thereby permitting movement of the auxiliarywheels.

[0013] In accordance with another embodiment of the invention, saidpipe-laying vehicle includes a travelling body having a longitudinalaxis, an undercarriage, a front pair of tracks and a rear pair oftracks, each said track being pivotally mounted to said undercarriagethereby permitting tilting movement of each track about an axis of tiltperpendicular to the longitudinal axis of said travelling body.

[0014] Preferably said longitudinal axis is parallel to the weldingaxis.

[0015] Preferably said pipe-laying vehicle includes at least a pair ofsteerable tracks and a steering mechanism operatively connected to saidsteerable tracks for steering the pipe-laying vehicle.

[0016] Preferably said pipe-laying vehicle includes means fordifferential movement of said tracks.

[0017] Preferably said transportable platform includes an end portionand a body portion, said end portion being hingedly attached to saidbody portion so as to be movable between an in-line configuration inwhich the portions are arranged substantially in line with each otheralong a longitudinal axis of said transportable platform and a foldedconfiguration in which said portions are arranged in an overlayingrelation with each other.

[0018] Preferably said end portion includes said outrigger.

[0019] Preferably said transportable platform includes an end portionand a body portion, said end portion being hingedly attached to saidbody portion so as to be movable between an in-line configuration inwhich the portions are arranged substantially in line with each otheralong a longitudinal axis of said transportable platform and a foldedconfiguration in which said portions are arranged side by side parallelto the longitudinal axis of said transportable platform.

[0020] Preferably said pipe guide includes rollers acting to align saidpipe string co-axially with the welding axis.

[0021] Preferably, each said roller has a profile substantiallycorresponding to the shape of said pipe string.

[0022] The invention also resides in a method of laying a pipelineincluding the steps of locating a mobile welding head in relation to theend of a laid pipe string, locating an end of a next pipe to be weldedin alignment with said welding head and said string, welding said nextpipe to the end of said string by magnetically impelled arc buttwelding, moving said welding ha into position for the welding of thenext pipe section thereby allowing laying of the extended pipe string.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Preferred forms of the present invention will be described by wayof example with reference to the accompanying drawings, wherein:

[0024]FIG. 1 shows a front elevation view of a pipe-laying vehicleaccording to a first embodiment of the present invention;

[0025]FIG. 2 is a plan view of the vehicle of FIG. 1;

[0026]FIG. 3 is an end elevation of the vehicle of FIG. 1;

[0027]FIG. 4 illustrates a method of loading the vehicle of FIG. 1;

[0028]FIG. 5 illustrates tilting of tracks;

[0029]FIG. 6 shows the vehicle of FIG. 1 negotiating a trench curve;

[0030]FIGS. 7 and 8 show alternative arrangements for the transport ofthe pipe-laying vehicle of FIG. 1;

[0031]FIG. 9 is a front elevation view of a pipe-laying vehicleaccording to a second embodiment of the present invention;

[0032]FIG. 10 is a plan view of the vehicle of FIG. 9;

[0033]FIG. 11 is an end elevation of the vehicle of FIG. 9;

[0034]FIG. 12 illustrates tilting of the vehicle of FIG. 9;

[0035]FIG. 13 is a detail of the outrigger of the vehicle of FIG. 9;

[0036]FIGS. 14 and 15 show the vehicle of FIG. 9 in a foldedconfiguration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Referring now to the drawings, there is illustrated in FIGS. 1-8a pipe-laying vehicle 5 according to a first embodiment of the presentinvention.

[0038] The vehicle includes a rigid platform 10 supported on twinpivoting steerable tracks 11 and 12. Mounted on the platform 10 is awelding head 13 within which the pipes to be welded are positioned inaxial alignment with each other and with the longitudinal axis of thewelding head (referred hereafter as a ‘welding axis’). Also mounted onthe platform 10 is an outrigger 14 which locates the laid pipe string 17by means of rollers 15 and 16 to ensure correct alignment of the laidstring with the welding axis.

[0039] Aligned with the welding axis is an in-feed bed 18 which receivesthe next pipe to be joined, and enables this pipe to be accuratelyaligned with the welding axis and the laid string 17. The in-feed bed 18is provided with rollers, not shown in the drawings, which support thenext pipe to be welded and enable the position of the pipe to beaccurately adjusted. One or more of those rollers may be powered.

[0040] Also mounted on the vehicle is a magazine 19, containing pipesready for laying. Pipes are moved from the magazine 19 to the in-feedbed 18 by hydraulically operated pipe handlers 20. Pipe handling can beperformed by a three or more degree of freedom hydraulic, pneumatic orelectrically driven mechanical device which is capable of picking thenext pipe from a cartridge on the pipe-laying vehicle or from a vehiclealong side the pipe-laying vehicle or from a stock pile on the ‘right ofway’ (ROW) or from a pipe string along the ROW.

[0041] The welding head 13 includes means (not shown) for clamping thestring and the next pipe, electrical connections for the supply of powerto the joint, and the magnetising devices which impel the welding arcaround the circumference of the joint. Also provided at the welding headis the forging system which delivers the forging force to the joint andcontrols the arc gap during the beating phase. This may be hydraulic,pneumatic or mechanical.

[0042] The welding head is attached to the platform 10 by means of aslide (not shown) which enables fine adjustment of the axial position ofthe head relative to the pipe string.

[0043] As mentioned above, pipes may be arranged in a magazine orcartridge, in which they are transported to the site. FIG. 4 shows sucha magazine 19, consisting of pipes clamped between two sets of stackingbars 21, being moved from a transport jinker 22 to the platform 10.

[0044] The illustrated vehicle is capable of negotiating terrain of thevarious kinds found on pipeline right-of-ways without externalassistance. It will be able to climb sand-hills without help frombulldozers, and cross soft or muddy ground. Manoeuvrability, stabilityand compactness of the pipe-laying vehicle is significantly enhanced bythe provision of pivotally attached tracks 11 and 12. As can be seenfrom FIG. 5, each track assembly is tiltable about an axis of tiltperpendicular to the longitudinal axis of the platform 10. As a result,various configurations of the ground-engaging portion of the pipe-layingvehicle can be achieved.

[0045]FIG. 6 illustrates the pipe-laying vehicle 5 negotiating a trenchcurve 25. As shown in FIG. 6, the tracks are pivotable about a verticalaxis. In a preferred embodiment, the pipe-laying vehicle includes meansfor differential movement of the tracks. The vehicle is steered byadjusting the speed of the track on one side of the vehicle in relationto the speed of the track on the other side. As a result, the entirevehicle can be rotated and translated through the differential movementof the tracks. Steering controls change individual track speeds througha variable speed differential or by individual motor drives. As aresult, the pipe-laying vehicle may readily negotiate narrow trenchesand make relatively sharp turns.

[0046] The vehicle may be transported as shown in FIG. 7 or FIG. 8. Inthe first of these arrangements, the platform length during transport isreduced by means of a hinged portion 23, and the outrigger 14 is hingedback onto the platform, while the tracks 11 and 12 are transported onthe platform 10. In the latter arrangement, the platform is made shortand narrow enough to be carried on unescorted road transport as shown,providing for the first time a vehicle capable of the functionsdescribed, yet capable of being transported on ordinary highways withoutescort and without delays.

[0047] In FIGS. 9 to 15 of the accompanying drawings there isillustrated a pipe-laying vehicle 30 according to a second embodiment ofthe present invention. The vehicle 30 includes a travelling body 35 anda rigid platform 37 rotatably supported thereon. The platform 37 isrotatable about a vertical axis by means of a hydraulic motor (notshown) or other means. In addition, the vehicle 30 includes pivotablemounting means (not shown) for tilting the platform 37 with respect tothe travelling body 35. As it can be seen in FIG. 12, the axis of tiltis perpendicular to the longitudinal axis of the platform 37. Thetilting of the platform is accomplished by means of a hydraulic cylinder(not shown) or other means.

[0048] In a preferred embodiment, the longitudinal axis of the platform37 is parallel to the welding axis.

[0049] The travelling body may be supported on trailed or driven wheelsor a single or multiple sets of tracks. In a preferred embodiment, thetravelling body is a self propelled vehicle supported on a single set oftracks 38. In the most preferred embodiment, the travelling body furtherincludes two pairs of auxiliary wheels 40 a and 40 b spaced from thetracks 38. The auxiliary wheels may be selectively activated to provideadditional support for the pipe-laying vehicle where ground conditionsrequire it. To this end, each of the auxiliary wheels is rotatablyattached to one end of a pivot arm 42, the other end of which ispivotally attached to the platform 37. In other embodiments, the pivotarm may be attached to the travelling body.

[0050] Similarly to the first embodiment, the pipe-laying vehicle isprovided with means for differential movement of the tracks. The entirevehicle can be rotated or rotated and translated through thedifferential movement of the tracks. By reversing one track entirely thevehicle can pivot on the spot.

[0051] The main body of the pipe-laying vehicle is rotatable relative tothe tracks. To this end, the main body of the vehicle is attached to thetracks through a ball bearing. For effecting the rotational movement ofthe main body, there is provided a hydraulic motor (not shown).

[0052] In common with the first embodiment, the vehicle 30 includes awelding head 45, an in-feed bed 47, a pipe handler 48, a pipe magazine49, and an outrigger 50. In addition, mounted on the platform 37 is anoperator's cab 52 including an operator console (not shown). The weldinghead 45 is slidably supported with respect to the platform 37 andmovable in an axial direction by a hydraulic cylinder (not shown) orother means.

[0053] Referring to FIG. 9, a full length pipe 28 of approximately 18 mis in position and entered into the welding head 45. The pipe issupported on five conveyor rolls 51 a-51 e. The pipe string 17 is shownleaving the rear of the pipe-laying vehicle through rear pipe guide (theoutrigger) 50.

[0054]FIG. 13 is provided to illustrate a preferred embodiment of theoutrigger 50. In this embodiment the outrigger 50 includes a strong andrigid structure 60 pivotally attached at P to the main body of theplatform 37. Rotatably supported on the structure 60 are two spacedapart sets 61 and 62 of polymer or elastomer coated rollers. The lowerset 62 supports the pipe string from below, the upper set 61 constrainsit from above. The abutting portions of the rollers substantiallycorrespond to the external profile of the pipe being processed. Theplacement of the sets 61 and 62 is such that the string is forced intoco-axial alignment with the welding head and the next pipe. Similarly tothe first embodiment, the outrigger 50 can be hinged back onto theplatform 37. In addition, the platform 37 includes a hinged front endportion 70 movable between an in-line configuration shown in FIG. 10 anda folded configuration illustrated in FIG. 15.

[0055] Referring now to FIG. 11, the pipe manipulator 48 transfers apipe from the pipe magazine 49 and places it on the conveyor rolls 51a-51 e ready for positioning in the welding head 45. The pipe magazine49 may be loaded by a device on the pipe-laying vehicle or by a sideboom tractor travelling along side the pipe-laying vehicle and pickingup pipes or bundles of pipes from the right-of-way.

[0056] Quality control of the pipe joints is preferably maintained byon-line monitoring, rather than by the use of non-destructive testing.This will enable pipes being directly laid into the trench from deliveryto the laying vehicle, thereby achieving significant savings in bothtime and personnel.

[0057] Not shown in the drawings, and variously associated with thevehicle or a separate vehicle such as a towing vehicle, are thenecessary sources of electrical power, typically a diesel generator, ahydraulic power source, which may be an electrically driven single ormultiple pump system, and the operator controls, including travel speedand direction control, manual and automatic weld control, pipemanipulator control, welding head fine position control. The dataacquisition system monitors all the process parameters and also providesreal time diagnostics for the operator.

[0058] While particular embodiments of this invention have beendescribed, it will be evident to those skilled in the art that thepresent invention may be embodied in other specific forms withoutdeparting from the essential characteristics thereof. Other embodimentsmay include marine vessels, sub-marine vehicles, rail-based vehicles,vehicles suitable for inland water and swamp conditions, etc. Thepresent embodiments and examples are therefore to be considered in allrespects as illustrative and not restrictive, and all modificationswhich would be obvious to those skilled in the art are thereforeintended to be embraced therein. It will further be understood that anyreference herein to known prior art does not, unless the contraryindication appears, constitute an admission that such prior art iscommonly known by those skilled in the art to which the inventionrelates.

1. An apparatus for magnetically impelled arc butt (MIAB) weldingincluding: a transportable platform; a MIAB welding head mounted on saidtransportable platform, said welding head having a welding axis; a pipeguide located rearwardly of said welding head and capable of engaging awelded pipe string to maintain alignment of said string with saidwelding axis; pipe feed means maintaining alignment of a next pipe to belaid with the welding axis and the pipe string.
 2. An apparatusaccording to claim 1, wherein: said pipe guide is mounted on saidplatform.
 3. An apparatus according to claim 1, further including: anoutrigger means extending rearwardly of said platform, said pipe guidebeing mounted on said outrigger means.
 4. An apparatus according toclaim 1, further including: means for the transfer of a pipe from a pipesupply to the pipe feed means, said feed means including an in-feed bedholding the next pipe to be welded in alignment with the welding axisand the welded string, said in-feed bed being mounted on saidtransportable platform.
 5. An apparatus according to claim 4, wherein:said pipe supply includes a pipe magazine, said pipe magazine beingmounted on said transportable platform.
 6. An apparatus according toclaim 1, further comprising: a travelling body, wherein saidtransportable platform is rotatably mounted on said travelling body, andhaving a substantially vertical axis of rotation.
 7. An apparatusaccording to claim 6, further comprising: pivotable mounting means fortilting said transportable platform relative to said travelling body. 8.An apparatus according to claim 7, wherein: the axis of tilt isperpendicular to the welding axis.
 9. An apparatus according to claim 7,wherein: said travelling body includes a tracked support having adirection of travel and said axis of tilt is perpendicular to saiddirection.
 10. An apparatus according to claim 6, wherein: saidtravelling body is rotatable about a substantially vertical axis ofrotation.
 11. An apparatus according to claim 6, wherein: saidtravelling body includes a main body and a tracked support, said mainbody being rotatable in relation to said tracked support.
 12. Anapparatus according to claim 6, wherein: said travelling body includesat least a pair of tracks for respective sides of said body.
 13. Anapparatus according to claim 12, further comprising: means fordifferential movement of said tracks.
 14. An apparatus according toclaim 12, further comprising: at least a set of auxiliary wheels forsupporting said pipe-laying vehicle, said set of auxiliary wheels beingspaced from said tracks, each of said auxiliary wheels being rotatablymounted to a pivot arm thereby permitting movement of the auxiliarywheels.
 15. An apparatus according to claim 1, further comprising: atravelling body including an undercarriage, a front pair of tracks and arear pair of tracks, said travelling body having a longitudinal axis,each said track being pivotally mounted to said undercarriage therebypermitting tilting movement of each track about an axis of tiltperpendicular to the longitudinal axis of said travelling body.
 16. Anapparatus according to claim 15, wherein: said longitudinal axis isparallel to the welding axis.
 17. An apparatus according to claim 15,wherein: said travelling body includes at least a pair of steerabletracks and a steering mechanism operatively connected to said steerabletracks for steering the pipe-laying vehicle.
 18. An apparatus accordingto claim 15, further including comprising: means for differentialmovement of said tracks.
 19. An apparatus according to claim 1, wherein:said transportable platform includes an outrigger.
 20. An apparatusaccording to claim 1, wherein: said transportable platform includes anend portion and a body portion, said end portion being hingedly attachedto said body portion so as to be movable between an in-lineconfiguration in which the portions are arranged substantially in linewith each other along a longitudinal axis of said transportable platformand a folded configuration in which said portions are arranged in anoverlaying relation with each other.
 21. An apparatus according to claim20, wherein: said pipe guide is mounted on said end portion.
 22. Anapparatus according to claim 20, wherein: said end portion includes saidoutrigger.
 23. An apparatus according to claim 1, wherein: saidtransportable platform includes an end portion and a body portion, saidend portion being hingedly attached to said body portion so as to bemovable between an in-line configuration in which the portions arearranged substantially in line with each other along a longitudinal axisof said transportable platform and a folded configuration in which saidportions are arranged side by side parallel to the longitudinal axis ofsaid transportable platform.
 24. An apparatus according to claim 1,wherein: said pipe guide includes rollers acting to align said pipestring co-axially with the welding axis.
 25. An apparatus according toclaim 24, wherein: each said roller has a profile substantiallycorresponding to the shape of said pipe string.
 26. A method of laying apipeline including: locating a mobile welding head in relation to theend of a laid pipe string, locating an end of a next pipe to be weldedin alignment with said welding head and said string, welding said nextpipe to the end of said string by magnetically impelled arc buttwelding, and moving said welding head into position for the welding ofthe next pipe section thereby allowing laying of the extended pipestring.
 27. An apparatus for magnetically impelled arc butt (MIAB)welding including: a transportable platform; a MIAB welding head mountedon said transportable platform, said welding head having a welding axis;a pipe guide located rearwardly of said welding head and capable ofengaging a welded pipe string to maintain alignment of said string withsaid welding axis; a pipe feeder adapted to maintain alignment of a nextpipe to be laid with the welding axis and the pipe string.
 28. Anapparatus according to claim 27, further comprising: a travelling body,wherein said transportable platform is rotatably mounted on saidtravelling body, and having a substantially vertical axis of rotation.29. An apparatus according to claim 28, further comprising: pivotablemounting means for tilting said transportable platform relative to saidtravelling body.